Biographical encyclopedia
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91 [156] BRAHE
BRAHE [156] Tycho Brahe, the son of a Danish nobleman of Swedish descent, is sup posed to have been one of twins. His brother, however, was either stillborn or died soon after birth. When one year old, Tycho was kidnapped by his child less uncle, and Tycho’s father accepted the situation. Tycho (usually known by his first name only, a Latinized version of the Danish, Tyge) was the last and, with the possible exception of Hipparchus [50], the greatest of the naked-eye astrono mers. In early life he studied law and philosophy at the University of Copen hagen, which he entered at the age of thirteen. He originally intended to go into politics, but in 1560 he observed an eclipse of the sun and switched to as tronomy and mathematics. Later he went to Germany for more training. In observing a close approach of Ju piter and Saturn in 1563, Tycho noticed that it came a month away from the time predicted for it by the tables pre pared under Alfonso X [100]. Conse quently he began to buy instruments with which to make observations for the preparation of new tables. He also began to cast horoscopes, and retained a life long interest in astrology, as did many astronomers of early modern times. (As trology was a far more lucrative pursuit than was genuine astronomy, and pa trons would far more willingly pay for horoscopes than for scientific findings.) In 1572, after a period in which al chemy temporarily claimed Tycho’s at tention, he finally made his mark, on the occasion of the flaring out (on Novem ber 11) of a new star. Hipparchus had noted one and used it as an occasion to prepare the first star map of importance. Another appeared in 1054, but it was observed only by Chinese and Japanese astronomers. These are not new stars but existing ones that explode and increase enor mously in brightness. Prior to the explo sion they may be too faint to be seen with the naked eye. Before the days of the telescope, they did indeed seem new stars. Tycho, observing the new star of 1572 (now sometimes called “Tycho’s star”), described it—and its astrological significance—in a fifty-two-page book of which a short version of the title is De Nova Stella (“Concerning the New Star”). Tycho’s star grew to be brighter than Venus and remained visible for a year and a half before fading out. Tycho had at first hesitated to publish the book, for he felt it beneath the dig nity of a nobleman to write books, but, fortunately, he overcame this snobbish impulse. Tycho’s book did three things. It es tablished the name “nova” for all ex ploding stars. It made the young man’s reputation as an astronomer. And, finally, since Tycho showed by parallax measurements, using the observations of other astronomers from distant places such as England, that the new star was too far for its distance to be measured, but certainly much farther than the moon, it struck a telling blow against the notion of Aristotle [29] that the heavens were perfect and unchanging. Tycho stretched his mind to the limit to imagine the size of the universe but, of course, he fell short. He thought the nova was three billion miles from earth, and the farthest star only four million miles beyond the nova. The stars, in other words, only occupied a comparatively thin shell just beyond the planetary system. The whole universe, by Tycho’s scheme, was only 6,100,000,000 miles in diameter—which is less than we now know the diameter of the planetary system to be. The king of Denmark, Frederick II, decided to serve as patron for his re markable young subject, who had flashed into prominence like a living nova, and to keep him from emigrating to Ger many, then the center of astronomical research. (The brain drain is by no means a modern phenomenon only.) To do this, he sponsored astronomical lec tures by the young man and, more im portant still, he subsidized the building of an observatory for Tycho on the is land of Hveen (now Ven), three square miles in area between Denmark and Sweden. Tycho built elegant buildings 92 [156] BRAHE
BRAHE [156] and outfitted them with the best instru ments he could make. Completed in 1580, it was the first real astronomical observatory in history and cost, it is es timated, about a million and a half dol lars of today’s money. He spared no ex pense, even building a five-foot spherical celestial globe. Here his reputation continued to grow and scholars from all over Europe visited him. So did rulers who fancied them selves scholars, such as James VI of Scotland, who visited Denmark in 1590 to marry a Danish princess. (Later, he succeeded to the English throne as James I .) In 1577 a great comet appeared in the sky and Tycho observed it carefully. Parallax studies showed that this object also was farther than the moon—an even worse blow against the perfection of the heavens. Aristotle, recognizing that the erratic comings and goings of comets could not be harmonized with the permanence and regularity of motion of other bodies, had insisted that comets were atmospheric phenomena. He was wrong. Galileo [166] in this respect agreed with Aristotle and was therefore behind Tycho here. Tycho, in studying the apparent mo tion of the comet, reluctantly came to the conclusion that its orbit could not be circular but must be rather elongated. This was a daring suggestion because in that case it must be passing through the various planetary spheres, and it could scarcely do that unless the planetary spheres did not exist. Such a possibility went much against Tycho’s personal leanings, for he was a conservative astronomer who would not abandon the notion of Ptolemy [64] and his Greek predecessors that the earth was the center of the universe. He was the last great astronomer to insist on it and to reject the heliocentric theory of Copernicus [127]. His great argument against it was the lack of stellar parallax, and he used this argument in his correspondence with Galileo to wean away the latter from Copernicanism. In this he failed. In his book on the comet, published in 1583, Tycho tried to strike a compro mise. He was willing to go so far as to suggest that all the planets but the earth revolved about the sun. Then, he insisted, the sun with its train of atten dant planets revolved about the earth. This would explain everything Coper nicus’ theory explained, but it did away with the celestial spheres of the Greeks, something Copernicus had not done. That was bothersome for if the spheres did not exist, what kept the planets in their orbits? This “Tychonic theory” was proposed, in part, to emphasize Tycho’s orthodoxy against his enemies at the Danish court —of whom he had many. Reminiscent of the views of Heracleides [28], it shared the fate of all halfhearted com promises in an age of desperate antago nism. It went almost entirely dis regarded. (Nevertheless, a half century later, Riccioli [185] was to give names to the craters on the moon, which the telescope of Galileo revealed. Riccioli, at least, ad mired the Tychonic theory, and so he gave Tycho’s name to the most promi nent and spectacular of all the craters visible from earth. Since he was an ad mirer of Greek astronomy, the book in which he did this was named the New
Hipparchus and Ptolemy to two large craters, centrally located on the moon’s surface. The name of Copernicus was given to a lesser crater and that of Aris tarchus [41] to quite a small one. The face of the moon still bears these names —a mark of the reluctance with which Greek astronomy was abandoned.) All through the years Tycho kept making magnificently accurate observa tions, reaching the limits that could be expected of the unaided eye. He was one of those who allowed for changes in the apparent position of heavenly bodies be cause of atmospheric refraction, and he corrected for instrumental errors as well. Nobody has ever observed more accu rately without a telescope. Where Ptol emy’s observations were correct to ten minutes of arc, Tycho’s were correct to two, which is about the theoretical limit 93 [156] BRAHE
BRAHE [156] for naked-eye observation. Tycho cor rected almost every important astro nomical measurement for the better. He observed the motions of the planets, par ticularly of Mars, with unprecedented accuracy. He prepared tables of the mo tion of the sun that were far better than anything previously done. He determined the length of the year to less than a sec ond. Even Tycho, however, could not free himself from his times altogether. He estimated the distance of Saturn, then the farthest known planet, at forty- five million miles, which seemed an enormous distance to the astronomers of the age, but was only one-eighteenth the real figure. The new accuracy in astronomy made calendar reform inevitable, and in 1582, under the sponsorship of Clavius [152] and of Pope Gregory XIII, it finally came to pass. Ten days were dropped, these having accumulated since the time of the Roman Empire because the lulian year was some minutes longer than the real year. To prevent further accumu lations in the future, every cycle of four hundred years was to see only ninety- seven leap years rather than one hun dred. The even-century years, such as 1700. 1800, and 1900, were not to be leap years, even though divisible by four, unless (like 1600 and 2000) they were also divisible by four hundred. This “Gregorian calendar” was quickly accepted by the Catholic nations, but only slowly accepted by the Protes tant and Greek Orthodox countries. (They preferred to be wrong with Sosig enes [54] than right with the pope.) It is now universally used throughout the civilized world, except where religious ritual demands the use of another. At about the time of the reform, chronology generally was being put on a scientific basis by Scaliger [154], But troubles were gathering about Ty cho’s head, mostly of his own making. Tycho simply could not forget he was a Danish nobleman and insisted on being an extraordinarily quarrelsome and arro gant one. He was harsh to his underlings and fought with everyone. In a foolish midnight duel at Rostock over some point in mathematics (it was 1565 and he was still only nineteen) his nose was cut off and he wore a false nose of metal for the rest of his life. Some have doubted the story, but a recent exhuma tion of his skeleton has confirmed it. Tycho’s vision of himself as a nobleman even led him to the rather humorous ex treme (according to tradition) of mak ing his astronomical observations in court dress. His patron, Frederick II, had the pa tience of a saint and endured it all, but he died in 1588 and his successor, Chris tian IV (who was to rule Denmark for sixty years), had a bit of a temper him self. After a few years he had had enough of the cantankerous and expen sive astronomer. He stopped the subsidy and forced Tycho out. (It should be mentioned that despite his haughty aris tocratic ways, Tycho married a peasant girl for love and made a good life with her.) Tycho left for Germany in 1597 and, at the invitation of the Emperor Rudolf II (whose coronation Tycho had witnessed years before), settled in new quarters in Prague. There he made his greatest discovery, for he found an assis tant in a young German named lohann Kepler [169], Tycho gave Kepler his painstakingly gathered observations and set him to working on the preparation of tables of planetary motions. That was the crown ing act of his life. When he died in 1601, after a short illness due, perhaps, to a ruptured bladder, he moaned, “Oh, that it may not appear I have lived in vain.” Kepler kept control of the data and con tinued to work with what were to prove to be results of the first importance. Tycho received an elaborate state funeral and Kepler saw to it, in fact, that Tycho had not lived in vain. He even loyally worked on Tycho’s scheme of the uni verse as he promised his teacher he would. Even Kepler, however, could not keep that alive. As for Tycho’s instruments—the glori ous equipment with which he had outfitted his Danish observatories—they were never used again. Within a decade of his death, Galileo’s telescope had made all of Tycho’s instruments obso
[157] BRUNO
STEVINUS [158] lete. They gathered dust and were finally burned during the first years of the Thirty Years’ War. [157] BRUNO, Giordano Italian philosopher Born: Nola (near Naples), Janu ary 1548 Died: Rome, February 17, 1600 Bruno, the son of a soldier, was bom of very poor parents, was educated at the University of Naples, and entered a Dominican monastery in 1563. He held unpopular opinions with fearlessness and had the ability to attract huge audiences by his speaking and writing. (He had also developed a system of mnemonics— a memory course, so to speak—which proved most popular.) Bruno developed mystical religious no tions that fit in with the opinions of Nicholas of Cusa [115] concerning the infinity of space, the inhabitability of other worlds, the motions of earth, and so on. He was also an atomist, and a believer in the circulation of the blood but everything was in the service of his dark and obscure mysticism; and it was his obvious and extreme religious heresy that made him persona non grata to all sides. Changing his name to Filippo Gior dano for safety, he fled first to Rome, then to Geneva. In Geneva, the Cal vinists ejected him and he went to Paris where he was patronized by Henry III, but where the Aristotelians also ejected him. He wandered over Europe, lectur ing at Oxford, England, in 1582 and in Germany for some years after 1586. In 1592 he was arrested in Venice by the Inquisition and charged with heresy. He might have gotten off by recanting as Galileo [166] was to do a generation later. However, no one since the days of Socrates [21] worked quite so hard and with such determination to secure his own conviction. As he said, his judges were more afraid of him than he was of his judges. After a seven-year trial he was burned alive at the stake. Intransigent to the last, he refused to accept the cross held out to him at the last moment. [158] STEVINUS, Simon (steh-vee'nus) Belgian-Dutch mathematician Born: Bruges, 1548 Died: The Hague, Netherlands, about March 1620 Stevinus was of illegitimate birth. His first position was as tax collector at Bruges, but he left this for broader fields in 1583, when he entered the University of Leiden. As quartermaster in the Dutch army under Maurice of Nassau, Stevinus worked out a system of sluices in the dikes that made it possible to flood the country quickly in case that were needed to stop an enemy. In math ematics he introduced the use of decimal fractions and was the first to translate Diophantus [66] into a modern language. He was also a firm partisan of the Co- pemican view of the planetary system. His main contributions to science are three: First, he showed in 1586 that the pres sure of a liquid upon a given surface depends on the height of the liquid above the surface and upon the area of the surface but does not depend on the shape of the vessel containing the liquid. He may be said to have founded the sci ence of hydrostatics. Second, he demonstrated the impossi bility of at least one variety of perpetual motion. He used for this purpose an end less chain about two inclined planes joined in a triangle and showed geomet rically that the chain would have to remain motionless. In this manner he continued the study of statics where the recently translated Archimedes [47] had left off. Third, in 1586 he performed the key experiment of dropping two different weights simultaneously and observed that they struck the ground at the same time —the experiment that seems indissolu bly, if incorrectly, wedded to the name of his younger contemporary Galileo [166], Stevinus was also the first (in 1599) to give values of magnetic declination 95 [159] NAPIER
NAPIER [159] for specific spots on earth—forty-three of them. In that same year, he published a de sign for a sail-propelled cart with front wheels that could be used to steer—a novelty. He also worked out the theory of navigating a ship according to a Mercator [144] map. The fact that Stevinus wrote in Dutch —and did so charmingly—helped mark the beginning of the end of Latin as the universal European language of learning. Other scholars of the era were beginning to use the “vulgar tongue,” Alberti [117] and Galileo for instance using Italian and Descartes [183] using French. The change was slow, however. Even a cen tury after Stevinus’ time Newton [231] was writing his great works in Latin. Stevinus married late in life, at sixty- four, but managed to have four children, two of each sex, before dying. [159] NAPIER, John (nay'pee-ur) Scottish mathematician
Edinburgh, 1550 Died: Merchiston Castle, near Edinburgh, April 4, 1617 Napier was born into the Scottish aris tocracy and was the eighth Laird of Merchiston. During his youth, he trav eled through a Europe split into warring camps by the Protestant Reformation. His native Scotland was itself in the pro cess of turning Calvinist. Napier was a wholehearted Protestant and in 1593 he published a bitterly anti-Catholic com mentary on the Revelation of St. John, the first Scottish work on biblical inter pretation. As a further sign of the hot passions aroused in those times, Napier spent considerable energy thinking out devices for destroying an invasion by Philip II of Spain, in case it should come. He planned a burning mirror like that ascribed to Archimedes [47], artillery that would destroy almost all life within a radius of over a mile, and armored war chariots and submarines. He did not pro duce any of these inventions and the only attempt made by the Spanish Ar mada anywhere near Scotland was de stroyed in 1588 by the small, maneu verable English vessels. No new inven tions were needed. It is no wonder, though, that Napier gained the reputation among the com mon folk of being a black magician. Some considered him unbalanced. Na pier’s firm belief in astrology and divina tion certainly did nothing to discourage such beliefs. Napier’s solid reputation rests upon a new method of calculation that first oc curred to him in 1594, the year after he wrote on the Bible. The result was a much more fruitful and memorable work. It occurred to Napier that all numbers could be expressed in exponen tial form. That is, 4 can be written as 22, while 8 can be written as 2s, and 5, 6, and 7 can be written as 2 to some frac tional power between 2 and 3. Once numbers were written in such exponen tial form, multiplication could be carried out by adding exponents, and division by subtracting exponents. Multiplication and division would at once become no more complicated than addition and sub traction. Napier spent twenty years working out rather complicated formulas for obtain ing exponential expressions for various numbers. He was particularly interested in the exponential forms of the trig onometric functions, for these were used in astronomical calculations and it was these which Napier wanted to simplify. His process of computing the exponen tial expressions led him to call them logarithms (“proportionate numbers”) and that is the word still used. Finally, in 1614, Napier published his tables of logarithms, which were not im proved on for a century, and they were seized on with avidity. Their impact on the science of the day was something like that of computers on the science of our own time. Logarithms then, like the computers now, simplified routine calcu lations to an amazing extent and relieved working scientists of a large part of the noncreative mental drudgery to which they were subjected. This relief was in tensified by a slight modification of log- Download 17.33 Mb. Do'stlaringiz bilan baham: 
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